JL does not make a 500/4. they make a 450/4, 300/4 they make a 500/5 and a 500/1. JL is more than loud on a 300/4 with TR speakers... its painful. XR series on a 450/4 would kill your hearing in 10 seconds flat. What do you mean by the Boston Acoustics amp being better? Did you mean the sub amp for your JL 10W7?